Stanford University
Stanford Univ/gravity Probe B/relativity Q&a
Click "Relativity Q & A". Over 200 questions and answers dealing with relativity (special and general), answered by NASA scientist Dr. Sten Odenwald. Answers are generally one paragraph, very clear and coherent.
PBS
Pbs Nova: Relativity and the Cosmos
This well-written explanation of relativity includes animations and pictures which may be helpful in understanding a tough topic.
Georgia State University
Georgia State University: Hyper Physics: Special & General Relativity
This site from the Georgia State University provides an interesting chart form of the ideas of relativity. Column 1 - Idea, Column 2 - Experiment. Each item is linked to its own page of explanation, which is well done. A nice type of...
Other
No Carolina St Univ: The Day the Universe Went All Funny
This site provides a very readable treatment of a really difficult subject. You still have to work hard at it, but this article can make relativity understandable.
Other
Uc Riverside: Usenet Relativity Faq
A physics usenet listing of frequently asked questions relating to relativity, answered by a number of scientists. Administrivia and Reference, Speed of Light, Special Relativity, General Relativity and Cosmology, Black Holes. Loads of...
University of St. Andrews (UK)
University of St. Andrews: Special Relativity
A historical approach to special relativity, giving all the events and names in the history of discovery of special relativity. Many links to these individuals.
University of St. Andrews (UK)
University of St. Andrews: General Relativity
A somewhat labored but thorough explanation of general relativity, beginning with Aristotle. Many links to the personalities connected to the article.
Georgia State University
Georgia State University: Hyper Physics: Michelson Morley Experiment
At this site from the Georgia State University is where the proof all starts. One must understand this experiment to have any confidence in relativity. Here's the experimental setup and a summary of the data.